Plant Functional Traits on Tropical Ultramafic Habitats Affected by Fire and Mining: Insights for Reclamation

Celestino Quintela-Sabarís,Guillaume Echevarria,John B Sugau,Reuben Nilus,Sophie Leguédois,Rimi Repin,Michel-Pierre Faucon

doi:10.3390/d12060248

Abstract

Biodiversity-rich tropical ultramafic areas are currently being impacted by land clearing and particularly by mine activities. The reclamation of ultramafic degraded areas requires a knowledge of pioneer plant species. The objective of this study is to highlight the functional traits of plants that colonize ultramafic areas after disturbance by fire or mining activities. This information will allow trait-assisted selection of candidate species for reclamation. Fifteen plots were established on ultramafic soils in Sabah (Borneo, Malaysia) disturbed by recurrent fires (FIRE plots) or by soil excavation and quarrying (MINE plots). In each plot, soil samples were collected and plant cover as well as species abundances were estimated. Fifteen functional traits related to revegetation, nutrient improvement, or Ni phytomining were measured in sampled plants. Vegetation of both FIRE and MINE plots was dominated by perennials with lateral spreading capacity (mainly by rhizomes). Plant communities displayed a conservative growth strategy, which is an adaptation to low nutrient availability on ultramafic soils. Plant height was higher in FIRE than in MINE plots, whereas the number of stems per plant was higher in MINE plots. Perennial plants with lateral spreading capacity and a conservative growth strategy would be the first choice for the reclamation of ultramafic degraded areas. Additional notes for increasing nutrient cycling, managing competition, and implementing of Ni-phytomining are also provided.

Highlights

Ultramafic soils are ecological or ‘edaphic islands’ due to their patchy distribution and contrasting soil conditions with respect to surrounding ‘normal’ soils [1,2]
In order to examine the effects of disturbance severity on resulting vegetation type on tropical ultramafic areas, we studied the soil properties and plant communities of areas that experienced moderate disturbance and severe disturbance
Observed values of soil variables are typical for ultramafic soils with pH around 7; Ca:Mg molar ratio

Summary

Introduction

Ultramafic soils are ecological or ‘edaphic islands’ due to their patchy distribution and contrasting soil conditions with respect to surrounding ‘normal’ soils [1,2]. The extreme edaphic conditions and isolated island-like distribution of ultramafic soils has led to the origin of numerous strict ultramafic endemic plant species, in tropical regions, such as Cuba, New Caledonia, and Southeast Asia [5,6,7]. Diversity 2020, 12, 248 areas in Sabah (North of Borneo, Malaysia) support a rich flora with more than 4500 species described to date and a very high proportion of strict endemics [8]. Ultramafic areas have been extensively mined for the recovery of different metals such as Ni (Ni sulphide deposits and Ni laterites) and Cr (chromite) [11]. As the few high-grade Ni sulphide deposits have become depleted, mining for Ni has shifted focus to Ni laterite deposits in tropical areas including

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